Electronic data storage devices such as magnetic disk readers, optical disk readers and tape readers are generally more efficient when provided with some type of automated apparatus for inserting, removing and storing the disks or tapes. In some cases, elevator type devices such as are found in jukeboxes have been used to load and unload the disks or tapes. Unfortunately, the jukebox type device is designed to maximize capacity rather than efficiency. Thus, it is usually necessary to go through an entire sequence of selecting from storage, moving to a reader, loading into the reader, reading, unloading and moving back to storage before a different selection may be made. Additionally, a jukebox type changing device is usually large and complex with associated high cost. Thus in an environment where high data productivity and low cost are important, the elevator type device is inadequate.
One alternative to the elevator type device is disclosed in U.S. Pat. No. 4,271,489 to Siryj et al., Jun. 2, 1981, and U.S. Pat. No. 4,286,790, to Siryj et al., Sept. 1, 1981. In the Siryj patents, a magazine rack holds a plurality of optical disks in a vertical orientation. A changer, which travels parallel to the magazine rack, secures one disk from the magazine rack and transfers the disk to a reading position. The changer moves along a ball screw to the proper position for selecting a disk to be used from the stationary magazine. The changer secures the disk from the magazine and places it in a change position while travelling into alignment with the reader. The changer then inserts the disk into the reader which scans the data from the disk. Unfortunately, the Siryj device is complex with many moving parts and must be operated as a complete unit in conjunction with a special reader.
Another type of automatic changer is disclosed in U.S. Pat. No. 4,519,055 to Gilson, May 21, 1985. The Gilson device comprises a carousel type cartridge storage module. In the center of the module, a changer rotates to select any one of the cartridges for reading. After selecting and gripping a cartridge, the changer moves the cartridge, in conjunction with a carrier to a reader below the storage module for scanning. Thus the cartridges must be moved horizontally from a storage position to a changing position and then vertically from the changing position to a reading/scanning position. The Gilson device, like the Siryj device, is fairly complex and must generally be operated as a complete unit with an included reader. Thus there is a need for a method and apparatus that is simple in operation and may, if desired, be adapted for use with a variety of reading devices.